More generally, writes Mintz, “one defining feature of young people’s lives today is that they spend more time alone than their predecessors.” They grow up in smaller families (22 percent of American children today are only children). They are more likely to have their own rooms than children in generations past, and to live in larger homes, which means the very architecture of their lives conspires against socializing with other family members. They also live in a nation of suburbs and exurbs, where neighbors and friends live farther away.

